Biomedical subjects

Claude Bouchard

Publications and source records attributed to Claude Bouchard.

130 records · Page 8Linked to original sources

PubMed2000

Familial resemblance in fatness and fat distribution.

The purpose of the study was to estimate the degree of familial resemblance in anthropometric indicators of fatness and fat distribution. The sample consisted of 327 Caucasian participants from 102 nuclear families. Indicators of fatness included the body mass index (BMI), the sum of six skinfolds (SF6: triceps + biceps + medial calf + subscapular + suprailiac + abdominal), and waist circumference (WAIST), while indicators of fat distribution included WAIST adjusted for BMI (WAIST(ADJ)), the trunk-to-extremity skinfold ratio, adjusted for SF6 (TER(ADJ)), and the first principal component of skinfolds, adjusted for the mean skinfold of the individual (PC1). A general familial correlation model was fit to the data, and a series of nested reduced models were also fit so as to test hypotheses about familial resemblance. The hypothesis of no familial resemblance (all familial correlations are zero) was rejected for all phenotypes, indicating that fatness and fat distribution aggregate within families. For the three indicators of fatness (BMI, SF6, and WAIST), the sibling and parent-offspring correlations were significant. Further, there were no sex or generation differences in the familial correlations. For the three indicators of fat distribution (TER(ADJ), WAIST(ADJ), and PC1), there was no parent-offspring resemblance; sibling resemblance was significant for TER(ADJ) and PC1. Further, spouse resemblance was not significant for WAIST(ADJ), but was for TER(ADJ) and PC1. For both WAIST(ADJ) and PC1 there were significant sex differences in the familial correlations. A combination of models including no sex or generation differences and no spouse resemblance was the most parsimonious model for BMI, SF6, and TER(ADJ). The environmental model (all correlations equal) was the most parsimonious for WAIST, the model of no sibling resemblance was the most parsimonious for WAIST(ADJ), and the model of no spousal resemblance was the most parsimonious for PC1. Estimates of maximal heritability range from 46-60% for fatness and from 29-48% for fat distribution, independent of overall fatness, suggesting that in this sample the heritability of fatness is greater than that for fat distribution. Further, the pattern of correlations, which generally includes no spousal resemblance but significant parent-offspring and sibling correlations, suggests the role of genes in explaining at least part of the heritability. Am. J. Hum. Biol. 12:395-404, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗

PubMed2000

Major gene effect on subcutaneous fat distribution in a sedentary population and its response to exercise training: The HERITAGE Family Study.

Complex segregation analysis of baseline subcutaneous fat distribution and the change in response to exercise training (post-training minus baseline indices) was performed in a sample of 482 individuals from 99 Caucasian families who participated in the HERITAGE Family Study. The sum of skinfold (SF) thicknesses at eight sites, and the waist and hip circumferences were measured at baseline and after completing a 20-week exercise training program. The trunk-to-extremity ratio (TER) was calculated by dividing the sum of skinfold thicknesses at four trunk sites (subscapular + suprailiac + abdominal + midaxillary) by the sum of skinfold thicknesses at four extremity sites (triceps + biceps + medial calf + thigh). While SF was used to assess total subcutaneous adiposity, TER and the ratio of the waist-to-hip circumferences (WHR) were used to characterize subcutaneous fat distribution. Baseline TER and WHR were age-adjusted and age-SF-adjusted within four sex-by-generation groups. The changes of SF, TER, and WHR in response to training were adjusted for age effects alone and for the effects of age and baseline values. Baseline SF was influenced by a multifactorial component (30%) plus a major effect that may be environmental in origin accounting for 47% of the variance. Baseline TER was influenced by a multifactorial component (18%) and a major codominant gene (q(2) = 0.10), which accounted for 56% of the variance. The major gene effect was independent of total subcutaneous adiposity. Baseline WHR was regulated by a major codominant gene (q(2) = 0.15), which accounted for 48% of the variance. However, this major gene effect for baseline WHR should be interpreted with caution, given the estimates of the tau's under the general model. No familial effect was found for the changes in response to training for these subcutaneous adiposity and fat distribution phenotypes. Am. J. Hum. Biol. 12:600-609, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗

PubMed1999

Genetics of abdominal visceral fat levels.

The purpose of this review is to explore the evidence accumulated thus far that suggests a genetic component to the observed variation in abdominal visceral fat (AVF) levels. The precise determination of AVF levels in humans is limited to methods such as computerized tomography and magnetic resonance imaging; thus, few studies have examined the role of genetic factors on this phenotype. Evidence from the Québec Family Study (QFS) and the HERITAGE Family Study indicates that between 50-55% of the variance in AVF levels, adjusted for total fatness, is attributable to genetic factors. Additionally, a major gene hypothesis for AVF was supported in the both the QFS and HERITAGE Family Study. However, after adjustment for total fat mass the support for a major gene was reduced, suggesting that a major gene which affects fat mass may also affect AVF either directly (pleiotropy), or indirectly. The search for candidate genes that may impact AVF levels is in its infancy, and few candidate genes have been identified. However, the glucocorticoid receptor (GRL), ss3 adrenergic receptor (ADRB3), and fatty acid binding protein 2 (FABP2) genes have been significantly associated with AVF or intra-abdominal fat levels in humans. In addition, three quantitative trait loci obtained from crosses of mice, the Do2, Mob4, and Qbw1 loci have been linked with mesenteric or abdominal fat and are thus considered positional candidate genes for AVF levels. The search for candidate genes or random genetic markers associated with AVF levels is a challenging prospect. However, given the significant heritability of this phenotype, the quest remains promising. Am. J. Hum. Biol. 11:225-235, 1999. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗

PubMedDate not supplied

The Pro12Ala PPARgamma2 gene missense mutation is associated with obesity and insulin resistance in Swedish middle-aged men.

BACKGROUND: A missense mutation in exon B of the adipocyte-specific isoform peroxisome proliferator-activated receptor-gamma2 (PPARgamma2) has recently been described, leading to the substitution of proline to alanine at codon 12, which causes a reduction in the transcriptional activity of PPARgamma2. The Pro12Ala PPARgamma2 polymorphism has been variably associated with obesity, insulin sensitivity, and dyslipidemia. AIMS AND METHODS: In the present study, we addressed the hypothesis that the Pro12Ala variant is associated with obesity and estimates of insulin, glucose, and lipid metabolism as well as circulating hormones including salivary cortisol in 284 unrelated Swedish men born in 1944. The subjects were genotyped by using PCR amplification of exon B of the PPARgamma2 gene followed by digestion with the restriction enzyme BstUI. RESULTS: Tests for differences between the PPARgamma2 genotypes revealed that the PPARgamma2 Ala homozygotes (n = 6) had higher body mass index (P = 0.022), abdominal sagittal diameter (P = 0.038), and nearly 3 times higher fasting insulin levels (P < 0.001) as well as higher HOMA insulin-resistance index (P = 0.011) compared to the PPARgamma2 Pro homozygotes (n = 186). This association was independent of body mass and fat distribution. In addition, subjects with the Ala/Ala genotype had lower total cholesterol (P = 0.012) as well as a trend toward lower high- and low-density lipoprotein cholesterol (P = 0.071 and P = 0.095) compared to the other PPARgamma2 genotypes. CONCLUSION: In summary, these findings both confirm and expand the current notion that the PPARgamma2 gene might play a role in the etiology of obesity and that genetic variability in PPARgamma2 is associated with variations in body fat mass and insulin sensitivity.

Diabetes Mellitus↗